Reciprocatory pump for supplying liquid fuel to internal-combustion engines



May 2, 1950 w E w NICOLLS 2,506,235

REcIPRocAToRiz P'uMPFoR SUPPLYING LIQUID FUEL TO INTERNAL-COMBUSTION ENGINES Filed June 18, 1948 2 1105177501 lflIHJXZ'zLcalls Patented May 2, 1950 REGIPRO(LNIQRYw PUMI. ROB SUEBLYING.

LIQUID FUEL.v T INTERNAL-CO1VIBUSTION Wilfrid; Edward Walter Nicoll's, Pinner; England, assignnrttm-GALVZ Limited; LondbmEns'land Application June .18, 1948,,SerialNo. 33,765 In Great'Britain Jime'20; 1947 4; Claims. 1:

This invention relates to reciprocatory pumps for supplying liquid fuel t'o-internal combustion engines, and has forits object to" enable motion to be transmitted hydraulically to the-piston of the pump ina siinple'and efi'ective' manner which preventsleakage of liquid fuel orair past the piston when thepump is in action;

The invention comprises in combination ahollow body part, an oilreservoir on the-body part, a spring-loaded hollow piston slidablein-the body party and; formed between. its ends. with.v an external circumferential groove which communicates with the interior--ofthepiston through a port or portsin\ the piston, valve-controlled inlet and outlet connections through which liquid fuel can flow. to and. from. the interior. of the body part under'the' action of the piston, a springloaded. plunger slidable in tiiepiston and": formed near its outer endwith a portor ports for establishingicommunication between-the interiorof the plunger and the reservoir when the plunger is in its outer position, and means for actuating the plunger, the arrangement being such that oil admitted through the port or ports in the plunger to the interiors of the plunger and piston can serve not only to transmit movement of the plunger to the piston, but also to fill the external groove in the piston and thereby serve as a lubricating and sealing medium.

In the accompanying drawing, the single figure represents a sectional elevation of a pump for supplying liquid fuel to internal combustion engines, constructed in accordance with the invention. s

In one manner of carrying the invention into effect, a hollow body part I is provided on which is secured an oil reservoir 2. Slidable in a vertically arranged cylindrical sleeve 3 in the body part is a hollow piston 4 which is closed at its lower end by a plug 5 and open at its upper end. The piston is loaded by a helical spring 6 acting on the lower end of the piston. The body part is provided with any convenient inlet and outlet connections 1 and 8 through which liquid fuel can fiow into and out of the body part under the action of the piston 4, these connections bein controlled by any convenient non-return valves. Thus the inlet valve may comprise a disc 9 loaded by a spring l0 arranged within a housing I I having lateral ports l2, the housing being held in position by the piston springB. The outlet valve may comprise a ball I3 located in a bore l4 and having a limiting stop member IS. The piston 4 is formed. between its ends with an external circumferential groove [6 which communicates with the interiorof the-piston through a port or' ports l T'formed in th-e piston near=its closed lower end;

Slidable in the hollowpiston and extending from. its: upper end into theoili reservoir 2 is a hollowplunger it which, is: closed at; its upper end and open at its lower end, the plunger. being loaded bya helical: springi l8- arranged between ahead 20 on: the. plungen and the: upper end. of the sleeve 3 above mentioned; Nearrits upper end the=:plunger. is. formed: with a; port or: ports 2-1" for establishing communication; between; the interior of the plunger and the reservoir 2 when. the plungerisin itsouter oruppen-position, as shown in: the figure; this: port or; ports being closable by the" upper-end; of the piston 4: at the-commencementoif the worhingstroke either plunger.

Mountedin; and extending fromthe reservoir 2% is v a; cam -operable; lever 22- which. is adapted to adt onzthaupper-end of and toactuatethe plun When the pump above described is in use, the interior of the plunger l8, that part of the interior of the piston 4 not occupied by the plunger, and the external groove I6 in the piston, are

' filled with oil, this being initially introduced through the port or ports 2| in the plunger. When the plunger is in its outer or upper position, the piston is in its upper or inner position in which a flange 23 on the lower end of the piston abuts against the lower end of the sleeve 3 in which the piston is slidable. In this condition the oil reservoir 2 communicates with the port or ports I! in the plunger. When the plunger is depressed against the action of its loading spring I9 by the actuating lever 22, oil is displaced from the interior of the plunger to the reservoir until the port or ports 2| in the plunger is or are closed by the adjacent end of the piston 4, whereupon the oil entrapped in the plunger and piston serves to transmit motion from the plunger to the piston, causing liquid fuel to be delivered through the outlet connection 8. As the inner end of the plunger l8 which acts on the oil is of smaller area than the lower end of the piston 4 Which acts on the liquid fuel, it follows that the pressure of the entrapped oil is greater than the pressure of the liquid fuel being discharged. Consequently the oil filling the external circumferential groove I6 in the piston serves not only as a lubricant but also as an effective sealing medium for preventing leakage of liquid fuel or air past the piston. Return movement of the plunger l8 under the action of its loading spring [9 is accompanied by return movement of the piston 4 also under the action of its loading spring 6 and this causes liquid fuel to flow into the body part through the inlet connection I. The

iston reaches its normal position (determined y contact of the flange 23 on the lower end of the piston with the lower end of the sleeve 3) efore the return movement of the plunger is completed, and the completion of this movement of the plunger serves to restore communication between the plunger port or ports 2| and the reservoir 2 thereby enabling the oil in the interiors of the plunger and piston to be replenished.

The output pressure of the pump above described may be conveniently regulated by limiting the pressure that can be imposed onthe entrapped oil by the plunger. For this purpose there is provided between the reservoir and the external groove in the piston a by-pass 24 containing a spring-loaded pressure relief valve 25.

It will be understood that the plunger can be actuated. by any convenient means, such as a cam or tappet for example, in place of the lever described and illustrated.

By this invention there is provided means for transmitting motion hydraulically to the piston of the pump in a simple and efiective manner which prevents leakage of liquid fuel or air past the piston, and which ensures adequate lubrication of the working parts.

Having thus described my invention, what I claim as new and desire to secure by Letters Patents is:

1. A reciprocatory pump for the purpose described, comprising in combination a hollow body part, an oil reservoir on the body part, a spring-loaded hollow piston slidable in the body part and formed between its ends with an external circumferential groove and with at least one port which establishes communication between the groove and the interior of the piston,

valve-controlled inlet and outlet connections that oil admitted through the port in the plunger to the interiors of the plunger and piston can serve not only to transmit movement of the plunger to the piston, but also to fill the external groove in the piston and thereby serve as a lubricating and sealing medium.

2. A pump as claimed in claim 1, having between the body part and piston, a sleeve in which the piston is slidable, the inner end of the piston being closed and having a flange adapted to engage one end of the sleeve.

3. A pump as claimed in Claim 2 in which the plunger is provided with a head and with a loading spring interposed between the head and one end of the sleeve in which the piston slides.

4. A pump as claimed in claim 1 and having a by-pass between the reservoir and. the external groove in the piston, and a spring-loaded pressure relief valve in said by-pass.

\VILFRID EDWARD WALTER NICOLLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,858,8'15 Becker May 17, 1932 2,364,781 Ericsson Dec. 12, 1944 

